wight



Aug. 5, 1924. 1,504,173

S. N. WIGHT AUTOMATIC TRAIN CONTROL SYSTEM Filed Maych 1a. 1921 2Sheets-Sheet 1 Aug. 5 1924.

S. N. WIGHT AUTOMATIC TRAIN CONTROL SYSTEM Filed March 18 941 2Sheets-Sheet 2 {lllllllll Patented Aug. 5, 1924.

UNITED STATES 1,504,173 PATENT OFFICE.

SEDGWICK N. WIGHT, OF hOCHESTER, NEW YORK, ASSIGNO-R TO GENERAL RAILWAYSIGNAL COlYIPANY, OF GATES, NEV YORK. A. CORPDRATION OF NEW YORK.

AUTOMATIC TRAIN-CONTROL SYSTEM.

Application filed March 18, 1921.

To all whom may concern Be it known that I, SEnowicK N. WIGHT, a citizenof the United States, residing at Rochester, in the county of Monroe andState of New York, have invented certain new and useful Improvements inAutomatic T rain-Control Systems, of which the following is aspecification.

This invention relates to automatic train control systems for singletrack railroads, and more particularly to the track equip ment and thecontrolling circuits of such a system.

On single track railroads protection must be provided for train movementin either direction, that is, protection for trains traveling inopposite directions toward .each other (opposing movements), and trainstraveling in the same direction as on double track railroads (followingmovements). These and other requirements for single track operation oftrains have been satisfied, so far as signal indication is concerned, bythe type of automatic block signal system now commonly known as anabsolute-perinissive-block system.

There are various types of train control systems employing ditl'erentforms of car apparatus and track devices, but in those types whichoperate in accordance with the principle of failure on the side oi?safety, the traclrway means is such that it is placed in the proceed orsafety condition by the closing of a circuit or the like, and is automatically changed to its danger or stopping condition when such circuitis broken.

The present invention i primarily directed toward providing anarrangement of circults and devices for use in connection with an A. P.B. system which will open and close the controlling circuits for thetrack de' vices of the train control system, in such a way that saidtrack devices will coinn'umicate the desired impulses or influences topassing trains in proper co iormity with the signal indication. Other.specitic objects and advantages of the invention will appearhereinafter.

In the accompanyingdrawing, 1 is a diagrammatic view showing onearrangement of the signals in an absolute-permissive-block system;

Figs. 2 and dare simplified diagrammatic views of two arrangements ofcontrolling circuits for the track element at a signal Serial No.453,302.

cation, where there are oppositely located opposing signals;

Fig. 4 is a diagrammatic view of one typical form of car equipment, andillus trates the way in which it cooperates with the track element; and

Figs. 5, 6, and 7 are simplified diagrammatic'views showing otherarrangements of controlling circuits for the track element, which aremore particularly applicable to a signal location where there is onlyone signal.

The controlling circuits embodying the invention have been shown in theform which they will take in connection with the particular A. P. B.system disclosed in my prior Patent No. 1,294,736, dated Feb. 18, 191.9,but by simple modifications and adaptations readily apparent to thoseskilled in the art, the same principles may be applied to A. P. B.systems oi other specific forms. Since the detail construction andoperation of the A. P. B. system of my prior patent is fully shown anddisclosed in said patent, it will be suthcient, in order to obtain aclear understanding of the present invention, to explain this A. P.R'system merely in a general way, and without attempting to point outthe detail construction, circuits and mode of operation.

Fig. 1 illustrates one arrangement of signals for an A. P. B. system.The stretch of single track (shown by a single heavy line) between twopassing sidings X, is divided into track sections AB-C etc., in theusual way by insulated joints 2. Sig na ls, designated S to S arelocated at intervals along this stretch of single track, and .in thearrangement shown, these signals are arranged in pairs. The two signalsS and S at each end of the stretch and controlling train movement intothe stretch, are known as the absolute or starting signals, and are madedistinguishable in some suitable way, as by the shape of the blade andmarker lights, from the other signals, these starting signals, when inthe stop position, signifying stop and stay. The other sig nals arepermissive signals, and when in the stop position, signify that thetrain may proceed in accordance with certain prescribed rules, expectingto find another train or other obstruction ahead.

The ,sg'cncral scheme of operation of the P. B. system schematicallyillustrated. in

Fig. 1 is as follows: When a train enters the stretch of single trackfrom either end, it causes all of the opposing signals to as sume thestop position, thereby blocking trains approaching in the oppositedirection. As this train travels through the stretch of single track,these opposing signals are held in the stop position until passed by thetrain. The signals behind this train are caused to assume in turn, thestop, the caution, and the clear positions, so as to permit follov7- ingmovements under signal protection the same as in double track blocksignal systems. The circuits and devices employed in obtaining thisoperation oi the signals are fully explained in my prior patent; and torthe purpose of describing the present invention, it is suilicient tonote that the track between successive signals, as S -S is di vided intotWo track sections, il-l3, each. provided with a track battery (notshown) and a track relay 3, the track relays being located at the endsof the track sections nearest the signals, and that there is a polarizedline relay L at each signal for controlling the position thereof.

In the present invention it is assumed that the track elements of thetrain control system are of the type which is caused to assume theinactive or proceed condition when a controlling circuit therefor isclosed. and the active stopping condition when sai d circuit is opened,this circuit including a soru-ce of energy, or being merely a conductingpath, according to the particular type of train control system. Whilevarious terms of trick elements may be employed in con nection With thisinvention, 1 have selected for illustration a track element Which actsinductively through an intervening air gap to influence suitable carapparatus. This track element produces its stopping eflect by virtue ofits magnetic qualities. and may be said to be of the inert type.Referring to big. 4, this track element T shown coniprises a U-shapediron core 4, with enlarged pole pieces 5, and is provided with a coil 0on each leg, said coils being Wound and onnected in series so as to becumulative in their effect when flux passes through said core.

The car element for cooperating with this particular form oi trackelement. comprises a similar ill-shaped iron core or yoke Y, withenlarged pole pieces 7, and is supported on the locomotive or othervehicle in any si able manner so as to pass directly over hie trackelement T. On one leg of the yoke is a coil or Winding 8. convenientlytermed the primary coil; and on the other leg is another coil 9,conveniently termed the sec onclary coil. he primary coil 8 is encrgizedby a battery 10, and to check the integrity of this energizing ircuit, abalanced relay ll This n is includedin said circuit.

relay R is provided with an armature L biased by an adjustable spring12, \vl" is adjusted so as to balance the attraction erted on thearmature When the normal cur rent flows. The armature 11 carries a heador" insulatin material which is disposed between movable contact springsor fingers liB-l/t cooperating with stationary contacts (indicatedconveniently by arrows). It the battery 10 should depreciate, or theenergizing circuit for the primary coil 8 break, the spring 12 overcomesthe attraction of the relay and moves contact spr ng l Way from itsiooperating lined contact thereby breaking the circuit which includes inseries the springs 13l land their fixed contacts Likewis it the primarycoil 8 should be short-circuited the current in the relay i1 increasesabove the normal and attracts the armature 11 in opposition to thespring 1), so as to move contact spring 13 out or en gageinent with itscooperating fixed contact. thereby 'lneaking the circuit.

The secondary coil 9 is connected to a relay ll which is constri'lctedthe same as the relay il with such changes in the wind' or the like thatmay be desirable to obta n the required operating characteristics. relayR and the secondary coil are couuectco in series With a battery 15.which i .ciiierably has a low voltage. it this circuit becomes broken,or the secondary coil 9 short-circuited, the relay it opens contacts inthe same way as above described. Also, it the normal current throughsaid relay is increased or decreased by induced voltage in the secondarycoil 9, the relay ll opens its (011i acts.

Any suitable term of train control apparatus may be governed by therelays and B; but since the type of this apparatus has no bearing uponthe present invention, there is illustrated. a device K. in the term oion elr-ictro-pneuinatic-valv which upon being deenergized may be used tovent the train pipe and apply the brakes at once. or set into operationspeed control equipment or any other sui able train control mechanism.The device included in a no'mellv closed circuit energized by a batteryl l6 ano. interrupted when the contacts of either oi the relays lt or ilare opened.

i i hen the coils 6 oi tic track element T are open-circuited, the corel 0t this element presents in eilcct a dead magnetic loop for the yoke Yof the car element and when said car element passes over this magneticloop, the reluctance of the partial magnetic circuit through said yokeis changed, thereby producii'ig a change in the in through the secondarycoil 9. This change in flux induces in the secondary coil 9 anelectromotivc-l orce, alternating in character, which alternatelyopposes and assists the voltage 01 the battery 1.5, thereby varying VIto the current in the relay It and causing it to open its contacts anddecnergize the device K. If the coils 6 of the track element are in aclosed circuit of low resistance, they serve to oppose or choke back thepassage of flux through the core 4:, so that as the car element passesover said core, there is no appreciable change in the flux through thesecondary coil 9, and the relay R is not operated.

Thus, if the coils 6 of the track element T are open-circuited, animpulse is transmitted to the passing vehicle which may be utilized inany desired way to control its movement; but if said coils are in aclosed circuit, the vehicle may pass without receiving such an impulse.In other words, with the circuit through the coil 6 closed, the trackelement is in its safety or proceed position, and With this circuitopen, said element is in the active stopping or danger condition.

The particular car and trackvvay equipment shown in Fig. l and abovedescribed forms no part of the present invention and is disclosed andclaimed in other applications.

According to the present invention, the track elements T are located onthe center line of the track so that they will co-operate with the carequipment on a vehicle traveling in either direction. It is necessary,therefore, to provide controlling circuits for the track element suchthat it will give the desired opposingand following protection, but willnot transmit a stopping impulse at the Wrong time; and the subjectmatter of the present invention consists primarily in an arrangement ofcontrolling circuits for accomplishing this result.

Fig. 2 showsone arrangement of controlling circuits embodying theinvention and particularlyv applicable for signal locations where thereare two opposing signals located opposite each other. Since the samearrangement is employed for each signal location, a description of onewill suffice for all. The signals S and S are controlled by polarizedline relays L and L respectively, in the usual way, and since thesecontrol circuits are well-known and are clearly shown, no detailexplanation will be given. It is noted here that these circuits havebeen shown according to the convention in which the letter B indicates aconnection to one teru'iinal of a battery or other source of curr andthe letter C a connection to the otlur terminal of said battery, eitherd rectly or through a common wire for the ystem.

The track. element T is preferably 10- cate-fl dire ly opposite theinsulated joints 2 between the track sections B and C. The coils 6 ofsaid track element are provided wi h two circuits in multiple. Wheneither of these circuits is closed, the track element T is in its safetyproceed condition, and with both of said circuits open, the track element is in its stopping condition. These circuits include neutral andpolar contacts on the line relays of the respective signals, so thateach of said circuits are open when the corresponding signal is in thecaution or stop position. For example, if the signal S is in the clearposition, the coils 6 of the track element are in a closed circuit whichmay be traced as follows: Commencing at one coil 6, wire 20, polararn'iature 21 of the line relay L wire 22, neutral armature 23 of saidline relay, and wire 24 to the other coil 6. This circuit will be openedat the polar armature 21 when the signal S is in the caution position,and at the neutral armature 22 when the line relay is deene-rgized togive stop indication. In other words, if either one of the signals S or8*, is in the proceed position, the track element is in the safetycondition, but if both of said signals are in either the caution or stopposition, said track element is in the active stopping condition.

The arrangement shown in Fig. 2 operates in the following manner.Suppose a train is traveling from left to right, in the direction oftrafiic governed by the signal S. As the train approaches track elementT, the opposing signal S is in the stop posi-- tion to block opposingtrain movements by virtue of the control of signal S fully plained in myprior patent.

The condition of the track element T, therefore, depends upon the linerelay L, which in turn is controlled by trains ahead of the train inquestion and traveling in the same direction. If there is no other trainahead, and the signal S is in the clear position, the coils 6 of thetrack element T are in a closed circuit, and train may pass with outreceiving a stopping impulse. If, however, there should be another trainahead, either in the next or succeeding block, and the signal S is ineither the stop or caution position, the coils 6 are open-circuited, anda stopping impulse will be communicated to the passing train. The samemode of operation is true for train movements in the opposite directionfrom right to left, the con trol of the track element being then governed in accordance with the indication of signal S the signal S beingin the stop position. In this way, the arrangement of controllingcircuits shown in Fig. 2 pro vides for governing trains traveling ineither direction in accordance with the nal indication. It should beunderstood that the car element is carried on the locomotive or theleading vehicle of the train so that it passes over the track elementbefore the line relay of the next track section in advance has beendeenergized by the front end of the train itself. ln most cases it isfo'iuiol preferable to support the car elen'ient directly back of thepilot in front of the ponytruck.

The same control shown in Fig. 2 may be applied to each of the pairs ofsignals shown in Fig. l; and except in one case, the stop ping impulseis transmitted oi'ily when it necessary for the train to stop. Toillustrate the x'ceptional case, suppose there is a train on the maintrack opposite one of the sidings X, then an approaching train about toenter the siding will receive a stopping impulse upon passing the signal3*, since both the signals S and are in he stop position. lt may or maynot be obict.- tio-nableto receive a stepping impulse under these saidcircumstances, depending upon the type of train control apparatus. Ifthe s stem is one enforcing speed restrictions, or one in which apermissive control is imposed, stopping impulse in this particularinstance does no harm, and strictly speaking, is proper. lf desired, thecontrolling condition of the track element at the starting signals maybe made dependi-uit upon the position of the switch leading to thesiding, or upon some manual action on the part of the trainman throwingthe switch.

Fig. 3 sho vs an arrangement operated in the same way as that shown in 2the only difference being that the controlling circuits for the trackelement are taken through circuit controllers U and operated by thesignals S and S instead of through neutral and polar contacts of theline relays. These circuit controllers and O are shown in accordancewith established convention, and are closed only when the correspondingsignal is in the clear position.

Instead of arranging the intermediate nals in pairs opposite to eachother, as shown in Fig. 1, a staggered arrangement of intermediatesignals is sometimes employed, that. is, signals S and S are omitted,and the intermediate signals S and S used alone to give the desiredopposing and following protection. In such an arrangement, there will beonly one signal at each intermediate signal location, so that thecircuit arrangeinent of Figs. 2 and 3 is not applicable.

Fig. 5 illustrates a modified construction for use with such staggeredintermediate signals. lln this arrangement, the track ele ment T isprovided with two multiple controllingcircuits as before, and one ofthese circuits is taken through the neutral and polar contacts of theline relay L, or through a circuit cont-roller operated by the signalThe other circuit includes a. front contact of the track relay 3 of thetrack section B next in the rear of the signal in question. VVhe-Ii atrain travels from left to right, in the direction. of trallic governedby signal 8*, it shunts-the track relay 3 M5042, rye

and opens one of controlling circuits for the track element 'l before itreaches clement, so that the controlling condition c said track elementis dependent upon tli indication of signal S as before. it t travelingin the opposite. direction, how will pass the track element beforeshuntiu the track relay 3 and consequently wil pass said trackelementwithout receiving a stoppin impulse, in spite of the fact thatthe signal S will be in the stop position.

Fig; 6 shows a similar arranger-m a: tn- 2. single s location. moreparticular u to give a stow impulse if thi signal is in the cautionsition though not necessarily if the signal is in the stop posi U011.

ln this arrangement. one of the twill controlling circuits for the trackelement T is taken through a back contact of the track relay 3 of thetrack section next in advance of the signal S. A train traveling in tl edirection of tratiic governed by the signal 5%" will pass the trackclement before dropping the track relay 3. and consequently thecontrolling condition of said track element is deptuidcnt upon theindication of said signal. A train traveling in the opposite direction,however, wil drop tra l: relay 3 and put the track element in the safetycondition, before the track element is passed.

Fig. 7 shows a modification of the an rangeinent illustrated in i (3,and provides for a stopping impulse at a stop sig nal, as well as acaution Slgnith which does not necessarily follow in the arra gementshown in 6. To illustrate with the arrangement shown .in i 6, supposethere is a train. on the track section C, then a following train willnot receive a stopping iinpulse, because the track relay 3 is down. Inthe modified arrangement shown in Fig. 7, the controlling circuit forthe track ele ment, which includes the back contact of the track relay 3also includes a back con tact 31 of the stick relay 30 associated withthe signal 5%, this stick relay being one of the characteristic parts ofthe .l. l sys tem. The control of this stick relay is fully explained inmy prior patent. and need be reviewed only briefly. The pick-up circuitfor said stick relay may be traced as foil lows: Commencing at oneterminal of the battery (indicated by B) through contacts of circuitcontroller 32 operated by s I 7 S and closed between about to 33, backcontac 3-5!- of track relay 3,

Wires 35-36, stick relay 30 to the other terminal of the battery(indicated by C). A train traveling from left to right picks up thestick relay, because it closes this pick-up circuit at back contact thecircuit controller 32 remaining closed for a short interval. Trainstraveling in the opposite direction donot pick up the stick relay bene-o ltlt) ill) llii

cause they open its pick-up circuit at the circuit controller 32 beforethey drop track relay PF and close its back contact 3 The stick relay30, when once picked up, is maintained energized by a stick circuit asfollows: Commencing at B, back contact 37 oi? line relay L, wire frontcontact 39 of the sticlr relay itself, wires 4:O 6, and stick relay 30,to (,l. assume there is a train on the track section C, the baclrcontact of track relay 3 will be closed, but it this train entered saidtrack section from the track section B, stick relay 30 was picked up, sthat the track clement behind said train in the track section C willtransmit a stopping impulse to a following train. A. train approachingin the opposite direction, that is, from right to left. is able to passthe track element T without receiving a stopping impulse in the same wayasdescribed in connection with Fig. 6, the st ck relay 30 in this caseremaining deenergized.

From the foregoing it will he observed that this invention provides anarrangement of controlling circuits for track elements by means ofwhichv the controlling condition of said elements may be automaticallyset up to conform with the signal in dication. even though the trainsmove in either direction past said track element. Generally stated, thisis accomplished by providing two controlling circuits for the trackelement, each of which may be said to correspond to one direction oftrain movement. If there is a pair of opposing signals at the signallocation, these two circuits for the track element are governed inaccordance with the signal indications. If there is only one signal at asignal location, one of these circuits is controlled in accord ance withthe indication of that signal, and the other by the track circuits insuch a way as to prevent an opposing train traveil. opposite to thedirection of traffic gO fel-l by said signal from stopping itself.

The particular constructions and arrange ments of circuits and devicesherein shown and described are obviously susceptible of variousmodifications and adaptations to suit various types of train. controlsystems and differentvforms 0'1": single track automatic block systems,and I desire t have it understood, therefore, that the embodiments ofthe invention shown and described are merely illustrative of: its natureand mode of operation.

lVhat I claim is:

1. In a train control system for single track railroads provided withtrack circuits, the combination with a track element having an inherenttendency to assume an active stopping condition and adapted when in thatcondition to communicate a stopping influence inductively through anintervening air gap to a train traveling in.

either direction thereby, said track element including an iron core anda Winding thereon, two separate control circuits for said track elementeach passing through said winding, said track element being in the sameinactive condition ii either of said circuits is closed, and meanscontrolled by a plurality of track circuits on opposite sides of thetrack element for separately and independently governing said circuits.

2. In a train control system for single track railroads provided withtrack circuits, and having oppositely located intermediate signalsbetween sidings, said signals governing trafiic in opposite directions,the combination with a track element associated with said signals andhaving two control circuits each adapted when closed to cause saidelement to asume the same inactive proceed condition, of means subjectedto the same controlling influence as said signals for controlling saidcircuits separately.

3. In a train control system for single track railroads provided withtrack circuits, and having oppositely located intermediate signalsbetween sidings, said signals governing tra'tfic in opposite directions,the combination with a track element associated with said signals andhaving two control circuits each adapted when closed to cause saidelement to assume the same inactive proceed condition, of circuitcontrolling means in each of said circuits closed when the trackcircuits governing the corresponding signal are not occupied.

4. In a train control system for single traclr railroads equipped withan absolutepermissive-block system having opposite intermediate signals,a track element opposite each pair of intermediate signals, and

means for placing each track element in the inactive condition unlessboth signals as sociated therewith are in the caution or stop position.

5. In an automatic train control system for single track railroadsequipped with an A. P. B. system having; pairs of opposite intermediatesignals, a track element opposite each pair of signals, and meanswhereby the controlling condition of said track elements isautomatically caused. to correspond with the indication of theassociated signal governing traflic in the direction in which a trainapproaches that track element.

6. In a system of automatic train control for single track railroads, atrack element comprising a non-magnetized iron core disposedsymmetrically with respect to the center line of the track so as toinfluence c0- operating receiving elements on the vehicle traveling bysaid element in either direction, a winding on said core, a normallyclosed deenergized circuit of low resistance including said winding andadapted when closed to place said track element in its inactivecondition, and automatic means for opening said circuit upon theapproach of a train to said track element from either direction ii thereis another trainin advance.

7, A train control system for single track railroads corprising, a trackelement ellecti e when in the stopping condition to transmni impulsesinductively to trains traveling in either direction, said track elementhas, j a control winding, two control circuits for said element eachpassing through said winding and each acting it closed to render saidelement ineffective to transmit an im* pulse to a passing vehicletraveling in either direction thereby, and automatic means formaintainin closed one or the other oi said circuits during the movementoi the train in one direction or the other past said element providedthere is no other track element in the direction 0]? which said passingtrain is traveling.

8. In an automatic train control system for single track railroadsprovided with track circuits, a signal governing trallic in onedirection, a track element opposite said signal and having a normallyclosed c ntrol circuit adapted so long as closed to cause said elementto assume its inactive condition, and means controlled by a trackcircuit in the I rear of the signal for opening said control circuit.

9. lln a train control system for single track railroads provided withtrack circuits, the combination with a signal, of a track elementlocated opposite said signal and comprising an iron core and a coilthereon, said track element having two control Clljcuits each includingsaid coil and adapted when closed to cause said element to assume itsinactive condition, means for controlling one of said circuits toconform with the indication of the signal, and means controlled by atrack circuit in the rear of the signal for governing the other controlcircuit.

10'. ln a system of train control for sin le tracli railroads havingtrack circuits sic nal governing tratlic in one direction. a tract:element located opposite the signal and having a normally closed controlcircuit which normally maintains said element in its inactive condition,and means for opening said control circuit before a train traveling inthe direction of traflic governed by said signal reaches said elementand for maintaining said circuit closed until after the first vehicleoil a train traveling opposite to the direction of the traflic governedby said signal has passed said track element.

1].. ln a train control system for single track railroads equipped witha block signal system oi": the type described, the combination with apair of oppositely located intermediate signals of said block signalsystem, a. track clement adjacent to the signals and comprising a coreand a coil thereon, a

a 1,50%,1 is

" each includin nt. in a train control systen,

raidroads equipped with i nal system of the type described, th'

1' 'on with a signal, a track eleme poseo substantially opposite tl e sicomprising non-magnetized core i thereon, a circuit including the coilant, closer. if the signal is in the proceed position, and anotherseparate c: s it incl d 5 the coil and governed by a 'aclr circuit n therear of the signal.

In a train control system tor track railroads equipped with a block sisystem of the type described the (Gilli/lul tion with a sin al. a trackelement disposed symmetrically with respect to the cente line oi thetrack and adjacent to the signal so as to influence cooperating carapparatus on a vehicle traveling in either direction the eby. said trackelement comprising an iron core and a coil thereon, two circuits eachpass ng through said coil, and automatic means comprising said circuitsfor main training said element in the same ii'iactire cor lion torvehicles inoi' ug in either Tllrection tl'iereliij-i unless there sanother train ahead in the direction o'li' trai'iic governed by saidsignal,

14;. In a train control system for sin 'le track railroads equhapcd witha block si system of the type described. the coiubia, tion with two adjaent track circuits oi block signal system, a track element disposedopposite the adjacent ends oil said track circuits and ha ing winding.and means l automatically by each trac i independently establish nc 0nuts at low resistance includiu s winding so long as that correspondindcircuit is not occupied.

ln :1 train controlsystem for single trach roads equipped with a blocksi 'nal system oi the type described. the combi; tion with a signal. amagnetic core extending transversely of the track and disposed adjacentto the signal symmetrically vith respect to the center line of thetrack, a winding on said core. and two separate circuits each includingsaid winding and governed separately by track circuits on opposite sidesof the signal.

16. In train control system tor single track railroads equipped with ablock signal system of the type described, the combina tion with twooppositely located intermediate signals, a track element opposite saidsignals and disposed symmetrically with re spect to the center line ofthe track, a circuit adapted when closed to maintain element in itsinactive condition, means sub jected to the same controlling influenceone of said signals for closing said circuit at times when the signal.may indicate proceed, a second. circuit also adapted when closed tomaintain. the track element in the same inactive condition, and meanssubjected to the same controlling influence the other of said signalsfor closing the secnd circuit when that signal indicates proceed.

i7. In a train control system for single tract: railroads, trackwayequipment for cooperating inductively with car-carried apparatus throughan intervening air gap comprising, two adjacent track circuits, a trackelement at the adjacent ends of said track circuits, said track elementbeing normally inactive, and automatic means for maintaining saidclement inactive so long as either of said track circuits is notoccupied.

l8. A, train control system for single track railroads for use inconjunction with a block signal system of the absolute-permissivebloclrtype described, comprising a track element located opposite a signal,said track element con'i n'ising a non-magnetized core, and auton'iaticmeans for governing the con trolling condition of each track element tocorrespond with the indication of the asso' ciatcd signal for trainsmoving in the direction of traflic governed by said signal, and formaintaininq said track element inactive until the first car of a traintraveling in the opposite direction has passed said element.

19. Inductive influence communicating means for block signal systems ofsingle track railroads comprising, a track element having a core and acoil thereon. and disposed symmetrically with respect to the center lineof the track, and automatic means for including said coil in a closeddeenergized circuit of low resistance for train movement thereby ineither direction unless there is another train ahead.

20. An automatic train control system of the type described, thecombination with a trackway block signal automatically governed inaccordance with the presence or absence of other trains ahead, a trackelement a iacent to said signal and having an in herent tendency tocommunicate the stopping influence, a non-energized control circuii" torsaid element adapted when closed to render said element inactive, andautomatic means for closing said circuit during the increment of avehicle in either direction by said signal unless there is another trainahead of the signal in the direction of traflic governed thereby.

21. In a train control system, the combination with trackway signals andcontrol means therefor constituting an absolute-permissivehloclr signalsystem of the general type described, track elements adapted to cooperate inductively through an intervening air gap with car-carriedapparatus and ar ranged to communicate an influence to passing cars toconform with the indications of each. signal, a polarized line circuitfor gov- Qljlllllg each signal, and means controlled by said linecircuit tor governing the contr0lling condition of the correspondingtrack element.

In a train control system, the combination with traclzway signals andcontrol means therefor constituting an absolute-permissive-block signalsystem of the general type described, a track element at each sig nalcomprising a core and a coil thereon, a circuit including said coil, anda polarized line relay governing each signal and also controlling saidcircuit.

23. In a train control system, the combination with trackway signals andcontrol means therefor constituting an absolute-perinissivc-block signalsystem of the general type described, a track element for each sig- :11comprising a non-magnetized core and a coil thereon, said track elementbeing adapted to communicate an influence to a passing vehicle unlesssaid coil is included in a circuit of low resistance, a polarized linerelay governing each signal, and a circuit of low resistance for thecoil of the corresponding track element governed by said relay.

In testimony whereof I afiix my signature.

SEDGWIGK N. WIGHT.

